30-06-2017, 09:52 PM
Hi.
Why are you condemning the rectifier? If the HT is stable and not dropping significantly over the soak test period then it's not the problem. If the valve is U.S. then the DC conditions would change. Hum changes with the volume control usually signify poor earthing or hum loops. One thing is the smoothing, forget ESR meters in valve HT smoothing, have the capacitors been replaced and decent ones used?
Why are you condemning the rectifier? If the HT is stable and not dropping significantly over the soak test period then it's not the problem. If the valve is U.S. then the DC conditions would change. Hum changes with the volume control usually signify poor earthing or hum loops. One thing is the smoothing, forget ESR meters in valve HT smoothing, have the capacitors been replaced and decent ones used?
